Art of grinding



Nov. 20, 1934. 1 ECASTER 1,981,220

' ART,oF GRINDING Original Filed. April 14. 192s 2 sheets-sheet 1 lll l lllnllllllllnmwm I Anas: fillr/l f A EMMMMMMWZ Y Nov. 20, 1934. .1. E. IcAsTER 1,981,220

ART OF .YGRINDING Original Filed April 14. 1926 2 Sheets-Sheet 2 aww/nto@ @oriented Nov.A i934 nire stra ABTGF GRINEING f '.io il.. Basten Covington, Ky., assigner, by mesne assignments, to Cincinnati Grinders Incorporated, Eincinnati, Ohio, a. corporation of Ohio origami application April 14', 192e, serial no.

102,067. Divided and this application December 12, 1930, serial No. 501,915

5 Claims. (Cl. 51- 278) This invention relates to improvements in the art of grinding and especially to a novel process for the production of articles of circular formv in cross section having a predetermined final axis. This application is a division of an application filed April 14, 1926, for a Grinding machine, Serial Number 102,067 which issued on February l0, 1931vas Patent No. 1,791,442.

Prior to the present invention it has been customary to produce articles of this type on what is `known as a center grinding machine in which the article is supported by the two rigidly fixed centers andr the work and wheel given a relative feeding movement, one toward the other. With articles of any appreciable length it has been customary to use a steady-rest or member/backing up the work to eliminate the variations due to spring of `the work or yielding of the centers during the grinding. These operations, however, have not been entirely satisfactory, particularly in the case of work which is initially out of round, or in which the centers are not concentrically located, due .to the fact that during the grinding of such articles the grinding wheel would strike the work only intermittently or with a chopping action and in addition, due to the fact that with such work it is impossible to so adjust the steady rest member as to continuously engage and support the' work prior to the rounding up thereof.

It is, therefore, one of the objects of the present invention to provide a novel method of producing work pieces of this character which shall make it possible to eliminate the individual dogging oi the work pieces, by providing a different manner of supporting said work pieces and effecting their rotation and in providing a backing member which .shall positively engage the work during the entire rotation thereof, and itself produce the pressure of the work against the grinding wheel, in place of depending upon the centers for applying the work pressure.

Another object of the present invention is the provision of an improved method of producing work piecesy in which the work is iioated in the throat of a centerless grinder and the oating movement of the work in the direction ofthe grinding wheel limited while it is being rotated about a definite axis.

A. further object of the invention is the provision of an improved process of concentric grinding of work pieces having -a plurality of portions thereon to be finished or ground concentric with a predetermined axis utilizing a l centerless grinder for the accomplishment of said process.`

Other objects and advantages of I the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings illu'strating` the several steps of the process and the mode by which they are accomplished and it is to1 be understood that any modifications may be-made in the exact order of the steps fof the process, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings:

Figure 1 is a fragmentary end elevational view of a centerless grinder for accomplishing the process of this invention.

Figure 2 is a fragmentary plan view of a slightly modified form of apparatus for use in utilizing the process of this'invention.

Figure 3 is a fragmentary view illustrating the progress of stock removal from the work piece.

' Figure 4 is a fragmentary view illustrating the general steps of the process.

Figure 5 is a diagrammatic view particularly illustrating the manner of limitation of size of the work piece.

Figure 6 is a sectional view taken on line 6-6 of Figure 2.

. In the drawings in which similar characters of 9 tion of the work, the operative surfaces of thetwo 5 wheels, therefore, at their adjacent point moving in opposite directions. Rising from the bed in-Y termediate these wheels is the bracket E, supporting the angle top work rest 10. This bracket, as shown` in Figure 2, also supports the floating headstock spindle 11, having a ball end 12 swiveled in socket 13 of adjustabler slide block 14.v This block is movable in a bore 15 of bracket 16,

:being locked against rotation by a screw 1'? engaged in the keyway 18 and being inwardly adjustable by screw 19. A pin 20 projecting from the sidesof ball end, riding in elongated slots 20 of the block 14, prevents rotation of spindle 1l but permits Aa free action of ball socket.

To control the position of this spindle a second or supplemental bracket' portion 21 -is provided having a passage 22 of asize to receive the inner end of the spindle 11, with suitable clearance -peri mitting limited universal oscillatory movement of I the spindle.

This bracket is further provided lwith a spring device 23 bearing against the end of the splndleto prevent the regulating wheel from lifting the work from the blade when the l. grinding wheel is not in contact with the work.

It is to b e noted that the parts Just described 'are on opposite sides of the grinding throat, as viewed in Figure 2.

One particularly desirable use fo a machine of l character is in the concentric production j of a second cylindrical face on "a two diameter work piece, as for example, the work piece illustrated in Figure 2 of the drawings, having the larger diam` eter portion 27, which hasbeen groundin a prior operation concentric with its centers by either center or centerless methods and having a second piece 27,-28 is provided with the customary centers adapted to receivev the points of the head and tailstock spindles l1. that one placed a't the forward side of the machine or to the left as viewed 'in Figure 2, is then brought in through the medium of hand wheel and screw 1 9", and the height 'a5 of the work rest and Supprting block are such that the points ofthe spindleswill automatically engage the centers, slightly backing up or raising the piece but notsuillciently to destroycontact :between the members 10 and 28. r

- -Iny grinding of work .by the centerless method, ,the work piece is supported on a work rest be- ;.tween grinding and regulating wheels and is al- -lowed to ilnd or establish its own center, the diameter being determined by the ilnal separation 5 .between grinding and regulating wheels. Inl

workoi' the present nature, however, it is neces- -V i sary that the axis of the work be determined by the position ofthe centers in its two ends. At xthe-same time, it 'is desirable that the grinding at an angle convergent to the operative face of the grinding wheely adjacent thereto. This angle `is preferably substantially parallel to a tangent to the regulating wheel at the point of contact with a finished work piece.

The action of the machine and the reason for this particular relationship of the parts will prob- `ably be best understood by reference to Figures 3,

4 and 5. Figure V3 illustrates the-actual operation of the machine in rounding up a work piece which was initially eccentric to the predetermined axis. ,M indicates the original exterior of the work pieceshown 'as substantially a true circle, but true as respects the center or axial line N and eccentric as respects the axial line O, which is determined by the position at which the two centers are placed 'in the ends of the work and about which,v therefore, final work -piece curve must be generated. The grinding is considered vas starting at the point P, being produced by an inward feeding-movement of the regulating wheel C pressing' the work against the grinding wheel. Q indicates the ilnal size of the work desired, being a circle generated about the point O as a center. It is, of course, to be understood that the dimensions here shown are greatly exaggerated to facilitate an understanding of the invention, as in actual. practice the total of stock removal would probably not exceed .050.l As the grinding starts at P and the vgrinding wheel vC is given a uniform inward movement by suitable manual or automatic mlehanism, the original grinding will be in the form'of a. uniform.

spiral path lR.. ,Thisgrinding' will continue and the shifting supportingI center or centers will move with the work toward the grinding wheel until stop screw 31 engagesth flat 30 on.` said spindle. 'Ihis limits the iurther' movement of the spindle toward the grinding wheel 'and' consequently limits the amount of stock which the grinding wheel can remove. The point at which this limitation occurs has been indicatedv as S. .As the regulating wheel continues to rotate Ithe work andmove inwardly -a dierent spiral of stock removal will be produced. As S is practically zerothe stock removal at a diametrically opposite point or T, .will be substantially double that of the initial spiral considering a constant move- -`ment of the regulating wheel. This'movement 50 bperationbe as continuous as possibleland the )work satisfactorily backed up during the'entire ygrinding operation. `This' presents a number of will continue in successive displaced spirals, as indicated, until the regulating wheel reaches its innermost position of movement determining the Adifficulties or problems which have for the first time been solved by the present machine; The

55; machine, it will be noted, has two floating centers A vbut one. of them lmay be a xed center and the other floating without limiting the benecial re- 4'sults Y'obtained from-the machine(l In 'any event.

'it is 'necessarywith a floating center that some wf' 'means'be provided for limitingthe'ilnalap'proach ofthe axis of the work to the wheel, thus limiting the'ilnal size oi' the work and insuring the work in cross section being a circle whose' center lieson the previously established In the 55 vof this result, use is made of la suitable stop for the oscillating spindle, this being shown in-Flgures2 andj 3, for examplejas pro- A duced by forming'a flat 30 on the spindle for en- {gagement by the end of the micrometer adjusting lo 'screw 31, provided with graduations 32, coupled is regulaung'wneelapbut on me contrary isformed with the index ilnger 33 to show the amount of adjustment. lAttention is particularly invited to thefact that this flat is not formed at right angles to thecommonlaxial plane of the grinding and final size of work piece when the spirals will have mergedinto the final outline Q.

. l'rms-limiting erect wm probably be better a'p- "130 preciated by vreference to Figure 5, in which Jthe stop; regulating wheel and work rest are diagrammatically indicated as being thethree points determining the final size and position of the work piece; the point U being shown where the tan gent to the regulating wheel'at the point ofcontact with the nal work piece' is also tangent to the surface of the work; the pointW being the point of 'contact of the surface o f thel work with the .supporting work rest- 'and the point X being the .point determined by engagement of the nat on the supporting spindlewiththe stop, "which may be considered'as a concentric circle oi' the work piece, as indicated by the dotted line circlel 'Y. The effect is-the same las though this were a second tangent or contacting member operating on the ilnal size of the work corresponding to thel dotted tangent X parallel with` the `iiat 30 ofthe headstock spindle. It will thus" be seen that the three contacting members indicated in the diaregulating wheel, the surface 30, as has been pregram by U, X and W form a. three point bearing, determining the position of the flnishedwork piece while the grinding wheel is a fourth member, the other members being so adjusted relative to the grinding wheel that the grinding wheel will produce the desired circular` outline Q removing all points on the surface of the work exterior to circle Q when thefnal position is determined as noted by being prevented by the three determinants from cuttinginto the work within said desired circle. f

It will be understood by those conversantmith the general grinding operations that after a work piece has been reduced to size and brought up against a stop, if the grinding wheel and work piece both continue to rotate for an appreciable period, there is a certain spring 'in the parts and general yieldability tending to produce a sparking out or i'lnal grinding and at the same time, if relative rotation ofthe parts continues, to cause a cutting below the exact predetermined size as established by the stop. This must be given particular consideration in connection with the present mechanism in which a considerable amount of grinding has to be done on one side of the piece, while very little grinding takes place on the oppcisite side. The present mechanism has, therefore, been designed to particularly take care of this point. In the centerless grinding operation of the work receiving throat for practical purposes may be considered as V shaped, that is to say the grinding is done above the axial plane connecting the grinding and regulating wheels, with the result that the,- wheels converge below therwork and as the size', of the work decreases, it tends to drop down into this `throat as is indicated by the centers Z, Z' and Z, as shownin Figure 4. This dropping of the center would, therefore, tend tovallow a slight stock removal if the stop were operated in a vertical plane. To accentuate this, however, and at the same time to permit of desired upward yielding movement of the parts and prevent clamping' or wedging between the stop and viously mentioned, is disposed at an,angle converging toward or approaching the grinding wheel surface so that there is both inward and downward movement as the diameter of the work decreases., In this manner it is possible for the stop to come into operation as indicated in Figure 5, limiting grinding action on the side of shorter radius and then the combined action of downward dropping and inward sliding which produces, in other words, the effect of a receding stop device, allowing limited amounts Aof material to be removed on the shorter radius for each maximum amount removed on the longer radius. As a result the surface of the shorter radius each time receives a slight but proper amount of grinding action, preventing the formation of flats or indentations therein by the grinding vwheel and insuring a more steady and uniform rotation of the work piece, due to the fact that there is thus maintained ya constant pressure between the work piece, regulating wheel and grinding wheel, until the work has been reduced to its nal finished form. This eliminates the irregular action of the grinding wheel which is characteristic of truing up work of this nature in the standard center grinding machines.

Of course, the same result here described could be attained by the use of a substantially straight stop member together with means for causing it to variably recede during the grinding operation as is'brought out, for example, in Figure 1. In this gure there is shown a rock lever 34 pivoted `to the bracket E and coupled with the regulating wheel slide D by a link 35, being so proportioned that the stop will move back a limited amount in proportion to the inward movement of the regulating wheel.

While the foregoing invention has been particularly illustrated and described as utilizing what is termed a centerless grinder, which is to say a grinder having a pair of opposed wheels and an intermediate work rest, it -is to be understood that the broad principles of grinding here illustrated are capable of adaptation to centertype grinders or the like in which a oating center is employed in combination with means for limiting its movement in the direction of thegr'inding wheel and in which suitable means are employed for urging and holding the work piece in contact with the grinding wheel.

What is claimed is:

1. The process of producing a work piece of circular form in cross-section with a predetermined axis in a centerless grinder, consisting in forming centers to establish the axis of the work piece, introducing the work piece between the grindingv and regulating wheels of a centerless grinder, supporting the work piece peripherally in said grinding throat for free movement relative to the wheels, as imparted'by the support, decreasing the width of the grinding throat to cause the desired stock reduction and limiting the movement lof the centers and established axis in the direction of the grinding wheel.

2. The process ofV producing a work piece of circular form in cross-section with a predetermined axis in a centerless grinder, consisting in forming centers to establish the axis of the work piece, 'introducing the ywor/k piece between the grinding and regulating wheels of a centerless grinder, supporting the Work piece peripherally in said grinding throat". for free movement relative to the wheels, as-imparted by the support, decreasing the width of the grinding throat to cause the desired stock reduction and limiting the movement of the centers and established axis in the direction of the grinding wheel and producing a relative receding action of the limiting mechanism, as the work piece approaches size whereby formation of ats is prevented.

3. The process of producing an article of circular form in cross-section with an axis other than its original axis of mass, consisting in supporting the article for floating movement between grinding andl backing members, spirally removing the surface of the article whereby a given reduction in diameter is effected for each revolution of the work., limiting the approachof the established' axis in the direction of the grinding wheel to cause the greater amount of stock reduction to take place on the longer radius of the work and producing a receding action of the limiting mechanism during grinding whereby continuous grinding is performed on all portions of the surface of the work until the same is reduced to nal circular form about the predetermined axis.

4. The process of producing an article of circular form in cross-section with a given axis of generationA for the peripheral surface thereof, consisting in holding the. article against an abrading wheel for continuous operation of the wheel on the surface thereof, and controlling the amount of stock removed from diierent arcs of said surface during each rotation, whereby the greater 5 thereof.

amount of stock. is removed on the longerk axis at each of said rotations to reduce the pi'ece to final form by continuous grinding of variable amounts Irom'the several" points on the periphery` tric with said preestablished regulating' wheels of a centeriess grinder, peripherally supporting the work for free oating movement transversely ofthe throat and laterally with respect to the throat, and positively limiting the amount of movementl of the predetermined axis in the direction of the point of engagement be- .tween the work and grinding wheel whereby the final work piece surface will be produced concen- JOHN E. CASTER. 

